A vacuum cleaner having a multi-part appliance housing which is formed by a lower housing part and an upper housing part is described in DE 44 21 214 A1. The upper housing part includes one or more separate cover parts. The lower housing part is divided by a partition into a motor fan chamber and a dust collection chamber.
Document DE 44 21 458 C2 describes a vacuum cleaner having a multi-part appliance housing where a housing cover pivotally mounted on cover hinges covers the dust collection chamber for a dust filter bag, and a replaceable exhaust or hygiene filter. The housing cover is hinged to the upper housing part which covers the motor fan chamber. When closed, the cover is flush with the upper housing surface in this area.
In both designs, the multi-part construction of the housing is configured such that the lower housing part is formed as a shell having raised side walls and including a motor fan chamber which is sealed off from the dust collection chamber. The motor fan chamber is covered by the upper housing part to which the housing cover is hinged. The housing cover is shaped such that it forms the upper housing surface and the lateral wall for the dust collection chamber. Furthermore, the housing cover has a storage compartment for vacuum cleaner accessories, said storage compartment being closable by a separate cover. The exhaust air of the vacuum cleaner is passed from the motor fan chamber through an exhaust filter. The exhaust filter is disposed below the housing cover. The housing cover has exhaust slots formed in the area covering the exhaust filter.
Due to the construction and arrangement of the cover, both designs place increased demands on the design of the seals in order for the negative pressure area in the dust collection chamber to be optimally sealed off from the exhaust or positive pressure area of the motor fan chamber. The pronounced dome shape of the housing cover, which also forms the lateral housing boundary of the dust collection chamber, is very complex to manufacture. Moreover, when the housing cover is open, the impression of an unstable configuration arises.
In order to avoid these drawbacks, modified constructions have been described for canister vacuum cleaners (for example, Miele S 700 series), where the multi-part appliance housing features a lower part having lateral walls that are raised in the shape of a pot to provide the boundary of the dust collection chamber. The pot-shaped, raised walls of the dust collection chamber are provided with a peripheral seal which sealingly abuts the housing cover portion for the dust collection chamber. The pot-shaped, raised walls of the dust collection chamber are laterally covered by an upper housing part enclosing the motor fan chamber and the dust collection chamber. A flat housing cover having a storage compartment for vacuum cleaner accessories is hinged to the housing portion that covers the motor fan chamber. The upper housing part portion enclosing the motor fan chamber has a seat for an exhaust filter. Also disposed on this housing portion are the ON/OFF button, the control elements for the suction power control, and the cord winder button.
The lower part including the lateral dust collection chamber walls, which are raised in the shape of a pot, is complex to manufacture in terms of tools, requiring large expensive injection molding machines. Moreover, unfavorable wall thickness ratios may result in sink marks in the transition region from the bottom plate to the raised lateral wall portions and the ribs formed thereon.
Furthermore, due to the increase in suction power, it has now become necessary to reinforce the walls of the dust collection chamber with ribs (see DE 93 12 061, FIG. 1). In the above-described constructions, where the ribs of the dust collection chamber bottom are formed from the lower housing part, this results in sink marks on the exposed outer side of the housing. It is therefore known to form the dust collection chamber as a separate insert (DE 84 32 010 U1), or to form a downwardly open insert on the upper housing part. In this manner, a double bottom is formed, which reduces the space available in the dust collection chamber, and thus the dust collection capacity. Since in all of the above-described variants, the side walls and bottom of the dust collection chamber form a closed pot, the molds forming the lateral ribs must be removed upwardly. This results in the requirement of using straight-surfaced, uncurved dust collection chamber walls having an exterior edge, the ribs extending into the opening of the dust collection chamber thus reducing the size thereof.